The present invention relates to moving pictures, and more particularly to block matching for picture motion estimation using Gray codes which provides a more hardware efficient technique for finding the "best fit" between a reference block in one picture frame and a corresponding block in a search area of the next picture frame.
A single monochrome digital video picture frame usually contains a set of sample values describing the luminance values at regular intervals vertically and horizontally within the picture frame. In a sequence of such picture frames any motion between each frame, due to camera panning or zooming, objects moving in the picture, etc., means that a pixel or group of pixels representing an object in one picture frame may have a corresponding set of pixels in the portrayal of the same object in the next picture frame of the sequence at a difference position within the frame.
Block matching is used to decide where a sampled block of pixels in one picture frame matches most closely to a block of pixels in the next picture frame. What is desired is an estimate of the motion for each block in one picture frame by obtaining the new position of the corresponding block, if it exists, in the next picture frame. With a limited amount of motion between frames, the search radius may be reduced and, therefore, the amount of computation required.
What is needed is a technique for obtaining a "best fit" between a reference block of one picture frame and a corresponding block in a search area of a next picture frame with a minimum amount of hardware.